svn commit: r325958 - in head: share/man/man9 sys/conf sys/kern
Mateusz Guzik
mjg at FreeBSD.org
Fri Nov 17 20:41:19 UTC 2017
Author: mjg
Date: Fri Nov 17 20:41:17 2017
New Revision: 325958
URL: https://svnweb.freebsd.org/changeset/base/325958
Log:
lockmgr: remove the ADAPTIVE_LOCKMGRS option
The code was never enabled and is very heavy weight.
A revamped adaptive spinning may show up at a later time.
Discussed with: kib
Modified:
head/share/man/man9/lock.9
head/sys/conf/options
head/sys/kern/kern_lock.c
Modified: head/share/man/man9/lock.9
==============================================================================
--- head/share/man/man9/lock.9 Fri Nov 17 19:25:39 2017 (r325957)
+++ head/share/man/man9/lock.9 Fri Nov 17 20:41:17 2017 (r325958)
@@ -26,7 +26,7 @@
.\"
.\" $FreeBSD$
.\"
-.Dd November 2, 2014
+.Dd November 17, 2017
.Dt LOCK 9
.Os
.Sh NAME
@@ -93,9 +93,6 @@ The timeout value passed to
.It Fa flags
The flags the lock is to be initialized with:
.Bl -tag -width ".Dv LK_CANRECURSE"
-.It Dv LK_ADAPTIVE
-Enable adaptive spinning for this lock if the kernel is compiled with the
-ADAPTIVE_LOCKMGRS option.
.It Dv LK_CANRECURSE
Allow recursive exclusive locks.
.It Dv LK_NOPROFILE
Modified: head/sys/conf/options
==============================================================================
--- head/sys/conf/options Fri Nov 17 19:25:39 2017 (r325957)
+++ head/sys/conf/options Fri Nov 17 20:41:17 2017 (r325958)
@@ -69,7 +69,6 @@ TEXTDUMP_VERBOSE opt_ddb.h
NUM_CORE_FILES opt_global.h
# Miscellaneous options.
-ADAPTIVE_LOCKMGRS
ALQ
ALTERA_SDCARD_FAST_SIM opt_altera_sdcard.h
ATSE_CFI_HACK opt_cfi.h
Modified: head/sys/kern/kern_lock.c
==============================================================================
--- head/sys/kern/kern_lock.c Fri Nov 17 19:25:39 2017 (r325957)
+++ head/sys/kern/kern_lock.c Fri Nov 17 20:41:17 2017 (r325958)
@@ -26,7 +26,6 @@
* DAMAGE.
*/
-#include "opt_adaptive_lockmgrs.h"
#include "opt_ddb.h"
#include "opt_hwpmc_hooks.h"
@@ -159,15 +158,6 @@ struct lock_class lock_class_lockmgr = {
#endif
};
-#ifdef ADAPTIVE_LOCKMGRS
-static u_int alk_retries = 10;
-static u_int alk_loops = 10000;
-static SYSCTL_NODE(_debug, OID_AUTO, lockmgr, CTLFLAG_RD, NULL,
- "lockmgr debugging");
-SYSCTL_UINT(_debug_lockmgr, OID_AUTO, retries, CTLFLAG_RW, &alk_retries, 0, "");
-SYSCTL_UINT(_debug_lockmgr, OID_AUTO, loops, CTLFLAG_RW, &alk_loops, 0, "");
-#endif
-
static bool __always_inline lockmgr_slock_try(struct lock *lk, uintptr_t *xp,
int flags);
static bool __always_inline lockmgr_sunlock_try(struct lock *lk, uintptr_t x);
@@ -661,10 +651,6 @@ __lockmgr_args(struct lock *lk, u_int flags, struct lo
uint64_t waittime = 0;
int contested = 0;
#endif
-#ifdef ADAPTIVE_LOCKMGRS
- volatile struct thread *owner;
- u_int i, spintries = 0;
-#endif
error = 0;
tid = (uintptr_t)curthread;
@@ -748,76 +734,7 @@ __lockmgr_args(struct lock *lk, u_int flags, struct lo
break;
}
-#ifdef ADAPTIVE_LOCKMGRS
/*
- * If the owner is running on another CPU, spin until
- * the owner stops running or the state of the lock
- * changes. We need a double-state handle here
- * because for a failed acquisition the lock can be
- * either held in exclusive mode or shared mode
- * (for the writer starvation avoidance technique).
- */
- if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
- LK_HOLDER(x) != LK_KERNPROC) {
- owner = (struct thread *)LK_HOLDER(x);
- if (LOCK_LOG_TEST(&lk->lock_object, 0))
- CTR3(KTR_LOCK,
- "%s: spinning on %p held by %p",
- __func__, lk, owner);
- KTR_STATE1(KTR_SCHED, "thread",
- sched_tdname(td), "spinning",
- "lockname:\"%s\"", lk->lock_object.lo_name);
-
- /*
- * If we are holding also an interlock drop it
- * in order to avoid a deadlock if the lockmgr
- * owner is adaptively spinning on the
- * interlock itself.
- */
- if (flags & LK_INTERLOCK) {
- class->lc_unlock(ilk);
- flags &= ~LK_INTERLOCK;
- }
- GIANT_SAVE();
- while (LK_HOLDER(lk->lk_lock) ==
- (uintptr_t)owner && TD_IS_RUNNING(owner))
- cpu_spinwait();
- KTR_STATE0(KTR_SCHED, "thread",
- sched_tdname(td), "running");
- GIANT_RESTORE();
- continue;
- } else if (LK_CAN_ADAPT(lk, flags) &&
- (x & LK_SHARE) != 0 && LK_SHARERS(x) &&
- spintries < alk_retries) {
- KTR_STATE1(KTR_SCHED, "thread",
- sched_tdname(td), "spinning",
- "lockname:\"%s\"", lk->lock_object.lo_name);
- if (flags & LK_INTERLOCK) {
- class->lc_unlock(ilk);
- flags &= ~LK_INTERLOCK;
- }
- GIANT_SAVE();
- spintries++;
- for (i = 0; i < alk_loops; i++) {
- if (LOCK_LOG_TEST(&lk->lock_object, 0))
- CTR4(KTR_LOCK,
- "%s: shared spinning on %p with %u and %u",
- __func__, lk, spintries, i);
- x = lk->lk_lock;
- if ((x & LK_SHARE) == 0 ||
- LK_CAN_SHARE(x, flags) != 0)
- break;
- cpu_spinwait();
- }
- KTR_STATE0(KTR_SCHED, "thread",
- sched_tdname(td), "running");
- GIANT_RESTORE();
- if (i != alk_loops)
- continue;
- }
-#endif
-
- /*
* Acquire the sleepqueue chain lock because we
* probabilly will need to manipulate waiters flags.
*/
@@ -833,25 +750,7 @@ __lockmgr_args(struct lock *lk, u_int flags, struct lo
continue;
}
-#ifdef ADAPTIVE_LOCKMGRS
/*
- * The current lock owner might have started executing
- * on another CPU (or the lock could have changed
- * owner) while we were waiting on the turnstile
- * chain lock. If so, drop the turnstile lock and try
- * again.
- */
- if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
- LK_HOLDER(x) != LK_KERNPROC) {
- owner = (struct thread *)LK_HOLDER(x);
- if (TD_IS_RUNNING(owner)) {
- sleepq_release(&lk->lock_object);
- continue;
- }
- }
-#endif
-
- /*
* Try to set the LK_SHARED_WAITERS flag. If we fail,
* loop back and retry.
*/
@@ -992,77 +891,7 @@ __lockmgr_args(struct lock *lk, u_int flags, struct lo
break;
}
-#ifdef ADAPTIVE_LOCKMGRS
/*
- * If the owner is running on another CPU, spin until
- * the owner stops running or the state of the lock
- * changes.
- */
- x = lk->lk_lock;
- if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
- LK_HOLDER(x) != LK_KERNPROC) {
- owner = (struct thread *)LK_HOLDER(x);
- if (LOCK_LOG_TEST(&lk->lock_object, 0))
- CTR3(KTR_LOCK,
- "%s: spinning on %p held by %p",
- __func__, lk, owner);
- KTR_STATE1(KTR_SCHED, "thread",
- sched_tdname(td), "spinning",
- "lockname:\"%s\"", lk->lock_object.lo_name);
-
- /*
- * If we are holding also an interlock drop it
- * in order to avoid a deadlock if the lockmgr
- * owner is adaptively spinning on the
- * interlock itself.
- */
- if (flags & LK_INTERLOCK) {
- class->lc_unlock(ilk);
- flags &= ~LK_INTERLOCK;
- }
- GIANT_SAVE();
- while (LK_HOLDER(lk->lk_lock) ==
- (uintptr_t)owner && TD_IS_RUNNING(owner))
- cpu_spinwait();
- KTR_STATE0(KTR_SCHED, "thread",
- sched_tdname(td), "running");
- GIANT_RESTORE();
- continue;
- } else if (LK_CAN_ADAPT(lk, flags) &&
- (x & LK_SHARE) != 0 && LK_SHARERS(x) &&
- spintries < alk_retries) {
- if ((x & LK_EXCLUSIVE_SPINNERS) == 0 &&
- !atomic_cmpset_ptr(&lk->lk_lock, x,
- x | LK_EXCLUSIVE_SPINNERS))
- continue;
- KTR_STATE1(KTR_SCHED, "thread",
- sched_tdname(td), "spinning",
- "lockname:\"%s\"", lk->lock_object.lo_name);
- if (flags & LK_INTERLOCK) {
- class->lc_unlock(ilk);
- flags &= ~LK_INTERLOCK;
- }
- GIANT_SAVE();
- spintries++;
- for (i = 0; i < alk_loops; i++) {
- if (LOCK_LOG_TEST(&lk->lock_object, 0))
- CTR4(KTR_LOCK,
- "%s: shared spinning on %p with %u and %u",
- __func__, lk, spintries, i);
- if ((lk->lk_lock &
- LK_EXCLUSIVE_SPINNERS) == 0)
- break;
- cpu_spinwait();
- }
- KTR_STATE0(KTR_SCHED, "thread",
- sched_tdname(td), "running");
- GIANT_RESTORE();
- if (i != alk_loops)
- continue;
- }
-#endif
-
- /*
* Acquire the sleepqueue chain lock because we
* probabilly will need to manipulate waiters flags.
*/
@@ -1077,24 +906,6 @@ __lockmgr_args(struct lock *lk, u_int flags, struct lo
sleepq_release(&lk->lock_object);
continue;
}
-
-#ifdef ADAPTIVE_LOCKMGRS
- /*
- * The current lock owner might have started executing
- * on another CPU (or the lock could have changed
- * owner) while we were waiting on the turnstile
- * chain lock. If so, drop the turnstile lock and try
- * again.
- */
- if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
- LK_HOLDER(x) != LK_KERNPROC) {
- owner = (struct thread *)LK_HOLDER(x);
- if (TD_IS_RUNNING(owner)) {
- sleepq_release(&lk->lock_object);
- continue;
- }
- }
-#endif
/*
* The lock can be in the state where there is a
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